Off the top of my head: Load/save format is a separate thing from what it uses to compute internally: http://www.imagemagick.org/Usage/basics/#hdri_formats . It most likely will affect speed. I don't think x2, however, if you bundle with IM7. A small factor, esp. if you compile IM with optimizing fl...

News from John Cupitt, lead dev of NIP2 (New Image Processor 2) http://www.vips.ecs.soton.ac.uk/index.php?title=Nip2 the GUI of the graphics library libvips, but also now for several ImageMagick operations: Hi Nicolas, I've just put up nip2 7.40.2: http://www.vips.ecs.soton.ac.uk/supported/7.40/win3...

I'm starting to think that the best way to improve sigmoidization is to replace by a blend of an enlargement through a gamma space and an enlargement through linear light.
In other words, the best way to improve sigmoidization >>for natural images<< is to use something else.

I think that using gamma > 1.8 to suppress the dark halos (hopefully without messing up midtones), linear to suppress the light halos (and preserve colors), and then blending the two putting more of the high gamma, may be a good way to get a good upsampling result. But maybe skipping the linear part...

... I just worry that two steps (gamma or sigmoidal) might add more blur (softness) that one can avoid with just one sigmoidal-contrast. If you blend two sharp versions of the same image (and of course they are perfectly aligned), the result should still be sharp. With less artificial acutance (bec...

I do not recall that it was my suggestion. Most likely not. Perhaps henrywho? Assuming I did not come up with this idea myself (at least within this circle), I'll ask him if this turns out to work well and he does not "show up". P.S. I don't think it was henriwho. Unless someone sets me straight, I...

Have you considered using a more symmetric "soft knee" curve rather than just gamma. see http://www.fmwconcepts.com/imagemagick/kneemap/index.php. Does it make sense to do both gamma>1 and gamma<1 in the same command, each with its own resize rather than processing the image twice and blending? Doe...

Not sure, but I think that just converting to a gamma space in order to work in a "smooth" perceptual space so as to minimize "dark halos", which with photographic material are more bothersome than the "light halos" may give better results with less tweaking than sigmoidizing. Something like magick ...